phelps



G. M. PHBLPS.

.Y MIGROPHONE TRANSMITTER. No. $30,925.' Patenteapr. 10, 188s.

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UNITED STATES PATENT OFFICE.

GEORGE M.

PHELPs, OF BROOKLYN, AssIGNOR To THE WESTERN .UNION TELEGRA'PH COMPANY, OF NEW YORK, N. Y. H

MIQROVPHONE-TRANs/Iirren.

SPECIFICATION forming pm of Letters Paten: No. sogezks, dated April 1o, lass. Application med ocwber s, 1ers. i

To aZZ whom it may concern:

Beit known that I, GEORGE MAY PIIELPs,

of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Microphone-Transmitters for Electric Speaking-Telephones, of which improvements the following is a specication. v v

The first part of my invention relates to the month-piece or speaking-tube. Its object is to enable the diaphragm to lie in a substantially horizontal position when the instrument is in use or in position for service, thereby protecting the cavity under the diaphragm from saliva and moisture from the mouth o'f the speaker, which end I attain by arranging the diaphragm in a substantially horizontal plane and causing the mouth-piece to Hare downward and Outward therefrom, so that the air waves or vibrations are deilected upward against the under side, of the diaphragm.

The next part of my invention relates to the construction of the diaphragm itself, its objects being to get rid of the harsh or rattling sound incident to microphone-transmitters as heretofore constructed, so far as my knowledge extends, and to secure the transmission of a. soft smooth tone, which ends I attain by making the diaphragm of alternate thin metal plates or thin sheets of soft paper or other suitable material. One disk of thin metal and .a disk of soft paper cemented together answer a good purpose; but I prefer to use two metal disks with an interposed disk of soft paper, all three being cemented together.

The objects of the next part of my invention are to secure a proper tension of the diaphragm while allowing it a slight degree of play in its fastenings and to prevent the transmission of rattlingjbr harsh sounds, which ends I attain byl combining a diaphragm, a. ring of soft paper or other suitable material lying loose under its bottom, a corresponding one lying loose on its upper surface, and a weighted metal ring resting on the top of the loose paper rIn Y 'Ighe next part of my invention relates to the method of mounting the contact points or pieces. Its object is to enable the operator to vary their degree of contact or pressure, which end I attain .by mounting a standard ou the center o f thediaphragm and securing an inertia-weight to a spring fastened on the standard, the weight carrying suitable carbons, (or other proper material for contact-surfaces,) with devices for adjusting the degree of press ure or area of the coutactsurfaces mounted on the'standard.

The subject-matter claimed is hereinafte stated.A i

The accompanying drawings represent all my present improvements as embodied in a single instrument.- Obviously, however,some of them may be used without the others and in machines differing in their details of construction from those herein shown.- It is also obvious that the details of the machine as to form, materials, and construction may be varied to a certain extent in various well-known ways without departing from the spirit of my invention. n

Figure 1 represents a plan or top view of my improved instrument, with the cover re moved to show the internal arrangements. Fig. 2 represents a vertical transverse section through the instrument on the line 2 2 of Fig. 1; and Fig. 3 represents a detail view on an enlarged scale, partly in section, through the diaphragm and contact-points to show the details of construction more clearly.

In order to carry out the first part of my invention to the best advantage, I preferably form the case, frame, holder, or support of the telephone of a solid block,`A, of wood or other suitable material, having a mouth-piece or speaking-tube formed in one side. This mouthpiece, it Willbe observed, is substantially iat or horizontal on top, while its sides Hare outward. Its bottom flares outward and downward, a transverse central opening being left at the point of convergence of thesedierent -sides or surfaces for the passage of the air or sound-waves to the diaphragm. y

The orifice of the mouth-piece by the construction above described, it will be observed, is much larger than usual in instruments of this class, thus enabling a larger area of soundwaves to be concentrated on the diaphragm, which latter under this' organization lies dat or horizontal when in use, the air-waves impinging on its under side, which construction prevents the deposition of saliva or moisture from the mouth of the speaker upon the diaphragm or the inner cavity of the mouth piece. Y

For the purposes of this vbranch of my invention the diaphragm may be mounted or secured in its support in any of the usual wellknownways. In order', however, tocar-ry out the next branch of my invention, I construct the diaphragm preferably of thin plates of metal and of thin sheets of soft paper'or other equivalent material-such as felt orsott vulcanizcd fiber, for instance. Y

A disk of thin metal and adisk of soft paper cemented together in well-known ways answers a good purpose; but I prefer to use thin metal disks c c'l with au interposed disk, c', of soft paper, all three being cemented. together.

The soft-paper disk between theftwo metal disks, forming the compound diaphragm C, should be slightly greater in` diameter than the metal disks, in order to protect the latter from a harsh` contact with thecase, thus se,-y curing the production of a purer tone or more perfect articulation. This diaphragm, so far as the purposes of this branch of ymy invention are concerned, may be clamped and held Yin any of the usual Well-known ways. In order, however, to carry out the object of the next branch of my invention in the best way, I form a cavity or recess in the top of the tele phone-ease support or holder, in which recess I place a ring, a, of soft paper or other wellknown equivalent material, which lies loosely-v on the bottom of the cavity. The diaphragm C is then placed on this ring and a corresponding ring, a', of similar material tothe other one is placed on the diaphragm. A weighted metal ring, D, (shown in this instance as a Banged ring,) is placed on top of this` dia-Y phragm and held inposition by turning-buttons d or other suitable fastenings, by which mode of construction the diaphragm, while loosely clamped to allow a slight degree of play either vertically or laterally, is securely held in position, the pressure exerted upon it being mainly due to the weight of the ring resting on its periphery.

The diaphragm fits somewhat loosely in its cavity, soas to allow aslight degree of lateral Y play. withoutcramping its edges.

The diaphragm may be removed, if desired, by loosening the screws of the buttons d and turning the buttons out of the way. Experience has demonstrated that this method of construction will produce a very smooth pure articulation, freefrom the usual harsh or rattling sounds to which this class of instruments is liable. The diaphragm thus constructed and mountedis capable of efficient use in the ordinary manner. In order, however, to carry out the next part of my invention, I `mount a metallic standard, E, centrally upon the diaphragm by means of a screw and nut, e, or in inertia-weight G is mounted on a plate-spring;V

g, secured to the arm e'. A radialslot, G, on the side of the' inertia-weight kopposite its pointof attachment tothe spring, fits over the other arm, e, whichthus serves as a guide to prevent the lateral displacement of the in-Y ertia-weight, while'allowing it to move freely Y up and down within the limited range inci-,l

dent to instruments of thisclass.

The platcspring g,which supports the inertia-weight, is electrically insulated by wellknown means at its point of attachment to the arm or standard e'. One of the line-wires,':v, is

connected to this insulated spring,y while thev` otheris connected to the other arm, e2, of the standard, the circuit passing through the contact-surfaces hereinafter mentioned. Theinertia-weight is preferably made of an annular shape, its central opening being closed at bottom by a plug, g', the inner end of whichplug is made of convex shape and faced with platinum, g. Y f

A short piece of tubing, h,of vulcanite, hard rubber, or other suitable insulating material, is inserted in the hole, `its bottom restingl on the plug,while its top is flush vwith the surface of the inertia-weight. jAthin disk, z', of carbon, of the usual construction is then laid on they convex surface of the plug and inside the insulating-tube h.. A double convexlens-shaped `piece of platinum, i', is then laid on the carbon disk and another carbon disk, i, laid on this piece, thus filling the hole iiushv with the upper surface of the Weight.

The adjusting-screw head Fis made convex on its under side and 'faced with platinum f and bears directly on the upper carbon disk above mentioned. In the arrangementI have shown all the `carbon surfaces are plane and the platinum surfaces convex; but it is obvi- TOO ous that substantially the same result might be obtained by making the platinum surfaces plane and the carbon surfaces convex, or by making the plane surfaces slightly concave, without departing from the spiritof the invention.

Under the organization above described the i circuit passes through'l the connecting-wire xv,

the spring inertia-weight, its plug, carbons,

Y and the adjusting screw and arme to the other connectingwire,y. Y Y A The pressure upon the contact-surfaces, and consequently the area of the points of their surfaces in contact, may be varied by means of the setscrew Fin a well-known way,

Theorganization above described secures -a very permanent adjustment, as when once adjusted the resilience of the spring upon which the inertia-weight is mounted tends to compensatethe very slightvariations in pressure incident to wear of the contact-surfaces from use.

The operation of the apparatus will readily be understood from the foregoing description.

As the diaphragm vibrates under the impulse ofthe sonnd-waves,thc pressure between the contact surfaces, and consequently the arm of the points of their surfaces in contact, will be varied, thus producing corresponding variations in the current passing through the n line-wire, as is well understood.

The inertia of the weight prevents it from following rapidly the minute vibrations of the diaphragm, while its resilience, due to its springconnection, compensates the coarser shocks and jars, which tend to produce the harsh and rattling sounds so common in this class of instruments.

I do not broadlyclaim herein whatisknown as an inertiatelephone,7 nor mounting the contact-surfaces upon the diaphragm, those devices being old but it will be observed that the organization of this instrument is such that the diaphragm carries the supporting standard and spring of the inertia-weightwith it. The diaphragm therefore may be thrown into vibration by the impact of the soundwaves without being impeded in its vibrations by the inertia of the weight, as it is when the action of the sound-vibrations is to deflect the diaphragm from its normal position directly against the weightinstead of away from it. The advantage of my arrangementin enabling the apparatus to respond accurately to the more delicate and rapid vibration is obvious.

1. The combination, substantially as hereinbefore set forth, with a diaphragm, of a month-piece eoustructed,substantially as hereinbefore set forth, with a dat top confronting said diaphragm and an outwardly-daring bottom to deflect the soundwaves upward and prevent the deposit of moisture in its inner cavity, as described. l

2. The combination, substantially as here inbefore set forth, of a diaphragm, a easing for supporting the same, and the mouth-piece formed in said casing and terminating in a flat top beneath said diaphragm and daring laterally and downwardly, substantially as described.

3. The compound diaphragm hereinbefore described, consisting of the combination of a thin metal disk or disks with a disk or disks of soft paper or equivalent material, the metal and paperV disks being arranged alternately and all cemented together to produce a smooth pure articulation.

4. The combination, substantially as hereinbefore set forth, of a metal disk or diaphragm, a disk of soft paper or equivalent material cemented to and projecting beyond the metal disk at its periphery, and aring clamping said disk or disks at or near the edges, substantially as described.

5. The combination, substantially as hereinbcfore set forth, of the case or holder, the ring of soft paper or equivalent material resting thereon, a diaphragm resting on the ring, another similar ring lresting on the diaphragm, and a weighted tension-ri ng resting upon the whole to allow slight play of the diaphragm while clamping it securely in place, as described. y

6. The combination; substantially as here inbefore set forth, of the case or holder, the downwardly-daring mouth-piece in one side thereof, the diaphragm in the top of the case, its softpaper rings, and the weighted metal tension-ring on that side of the diaphragm opposite the mouthpiece.

7. The standard mounted upon the diaphragm and provided with two arms,'one carrying by means of a yielding support the inertia-weight, the other the adj usting-screw for the contact-surfaces, substantially as herei nbefore set forth.

S. Theeombiuation, substantially as hereinbeforc set forth, of the diaphragm, the standard mounted thereon,the platespring mounted on the standard, and the inertia-weight supported solely by the spring and containing a scat for the electrode, whereby the diaphragm may be thrown into vibration by the impact of the sound-waves without being impeded by the inertia of the weight. Y

9.v The combination, substantially as hereinbefore set forth, of a diaphragm, astandard, a yielding spring, disks or buttons f carbon or other suitable material interposed between said standard and spring, a weight modifying the pressure upon the carbon, and adjusting mechanism for regulating the normal pressure upon the disks or buttons, substantially'as described.

`10. The combination, substantially as hereinset forth, of a diaphragm, a weight, its dexible support, an electric-circuit regulator composed ot' carbon or other suitable material, and a connection at or near the 'center of the diaphragm in line with the carbon and weight.

11. The combination, substantially as hereinbefore set forth, of the standard and the annular inertia-weightfor modifying the pressurein a microphone-transmitter mounted upon a spring and provided with a guide-slot moving over the standard, substantially as hereinbefore set forth.

12. The combination, substantially as hereinhefore set forth, ofthe case, the downwardly-flaring mouth-piece in the side thereof, the weighted clamping-ring, the diaphragm in the top of the case, the standard mounted on the diaphragm, and the inertia-weight and its su pporting-spring mounted on the standard.

13. In a microphonetransmitter, the combination, vsubstantially as' hereinbefore set forth, of the convex platinum-faced screw with the convex platinum-faced plug, carbon disks, and interposed platinum lens.

14. The combination, substantially as heieinbefore set forth, of the forked standard, the

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inertia-weightand its contact buttons or eleo- In stimony whereof I have hereunto sub- -xo l trodes mounted on one branch thereof, and the scribed my name. adjusting-screw mounted 0n the other brauch. v

15. The combination, substantially as here- G. M. PHELPS.

5 inbefore sob forth, of the diaphragm,the forked I standard, the iuertiaweghb, its insulated sup- Witnesses:

porting-spring, contact buttons or electrodes, FRANK L. POPE,

and 'connecting-wire mounted ou said stand- 'Wm ABNoUX. 

